New ATLAS publication

Measurement of the tttt production cross section in pp collisions at sqrt(s)=13 TeV with the ATLAS detector” has been submitted to JHEP. Members of the IFAE-ATLAS team (Aurelio Juste, Nicola Orlando, and Anil Sonay) have played a leading role in this publication, from designing the analysis strategy to the final multivariate technique and statistical analysis employed.

This paper presents a measurement of the four-top-quark production cross section in final states with a single lepton or an opposite-sign lepton pair in association with multiple jets using the full Run 2 dataset collected with the ATLAS detector. With four top quarks produced per event, this is a very rare Standard Model process with a predicted cross section of only 12 fb, and thus is very sensitive to beyond-the-SM (BSM) contributions. A sophisticated event categorization and multivariate technique is used to discriminate signal from background events. The result of this analysis is combined with a previous measurement in multilepton final states. The combined cross section is measured to be a factor of two higher than the SM prediction, although compatible with it within 2.0 standard deviations. The corresponding observed (expected) signal significance is .7 (2.6) standard deviations over the background-only prediction.

The IFAE team is currently working on an improved analysis targeting BSM production of four-top-quark events. Stay tuned!

More information on the ATLAS Physics Briefing


Latest Group News

New Member

New Member in the ATLAS group

November 23, 2021

Jack Harrison has just joined the ATLAS group as a PhD student with an INPhINIT Fellowship.

Instrumentation Milestone

HGTD project milestone achieved

October 6, 2021

Wafers with the ALTIROC2 chip were received this week. This is a major milestone for the HGTD project.R. Casanova played a leading role in the design of the digital part of the chip and its verification.

New Position

Martine Bosman elected as a Fellow of the European Academy of Sciences

October 6, 2021

Martine Bosman was recently elected as a Fellow of the European Academy of Sciences (EurASc). EurASc is a fully independent international association of distinguished scholars that aims to recognize and elect to its membership the best European scientists with a vision for Europe as a whole, transcending national borders, and with the aims of strengthening European science and scientific cooperation.